esha i 
Fs c 
to observe it, 
PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. ye 
Owing to the fact that Heidenschild’s results formed the subject 
- of an inaugural dissertation, and were not as far as I am aware, 
published in any journal, I had not the advantage until recently 
of consulting his paper in Sydney, and I regret that on this 
account I omitted to mention his work in a previous publication 
of my own on this particular aspect of the physiological effect of 
the injection of Pseudechis venom.! We were however, both 
forestalled by Fontana,? who more than one hundred years ago 
noticed that in those experiments which were followed by the 
sudden death of the animal, the blood was solid throughout the 
greater portion of the venous system, and who expressed his 
opinion that the clotting of the blood in the living animal caused 
death by arresting the circulation. Fontana, as previously 
mentioned, also noticed the permanent fluidity of the blood in 
other cases of viper poisoning, and he would appear to have 
wondered greatly that two such apparently opposite effects could 
be produced by the operation of the same agency. 
Immediately after the introduction of the venom into a vein, 
the coagulability of the blood increases, and this increase of 
coagulability, in the case of moderate or large doses (more than 
‘0001 gramme per kilo.), culminates in intravascular clotting of 
greater or less extent. The smallest dose which I have found 
to produce complete clotting in the systemic circulation was 
9:00015 gramme per kilo. Such a dose, however, usually in dogs 
gives rise to thrombosis limited to the portal vein and its branches, 
and inhibition of coagulability elsewhere. 
The injection of small doses,—i.e. below 0-0001 gramme per 
Kilo.—also gives rise to a condition of increased coagulability of - 
the blood. This increase however, only manifests itself for an 
extremely short time, and samples must be drawn within two 
minutes from the time of the introduction of the venom, in order 
This transient positive phase is succeeded by a 
Prone re: 
Prepac na en 
1 
Journal of Physiology, Vol. xv., p. 380. 
Stars -—This observation of Fontana’s was also unknown he Pe er 
*eently, as a copy of his work was not procurable in Sy 
